Tag: Metabolism of Triacylglycerol

Metabolism of triacylglycerides

In the liver cells, triglycerides are formed primarily in the following organelle:

A

Rough endoplasmic reticulum

B

Smooth endoplasmic reticulum

C

Golgi apparatus

D

Ribosomes

Q. 1

In the liver cells, triglycerides are formed primarily in the following organelle:

A

Rough endoplasmic reticulum

B

Smooth endoplasmic reticulum

C

Golgi apparatus

D

Ribosomes

Ans.

B

Explanation:

Synthesis of triacylglycerols mainly takes place on the smooth endoplasmic reticulum of the liver but can also be generated in adipose cells.

Regardless of the location of synthesis, the starting molecule is glycerol-3-phosphate produced in liver from glycerol stores or in adipose cells from dihydroxyacetone phosphate, the product of the fourth step of glycolysis.

A 32-year-old woman who has been on oral contraceptive pills for 5 years, developed symptoms of depression, irritability, nervousness and mental confusion. Her hemoglobin level was 8g/dl. Biochemical investigations revealed that she was excreting highly elevated concentrations of xanthurenic acid in urine. She also showed high levels of triglycerides and cholesterol in serum. All of the above are most probably related to a vitamin B6 deficiency caused by prolonged oral contraceptive use except:

A

Increased urinary xanthurenic acid excretion

B

Neurological symptoms by decreased synthesis of biogenic amines

C

Decreased hemoglobin level

D

Increased triglyceride and cholesterol levels

Q. 2

A 32-year-old woman who has been on oral contraceptive pills for 5 years, developed symptoms of depression, irritability, nervousness and mental confusion. Her hemoglobin level was 8g/dl. Biochemical investigations revealed that she was excreting highly elevated concentrations of xanthurenic acid in urine. She also showed high levels of triglycerides and cholesterol in serum. All of the above are most probably related to a vitamin B6 deficiency caused by prolonged oral contraceptive use except:

A

Increased urinary xanthurenic acid excretion

B

Neurological symptoms by decreased synthesis of biogenic amines

C

Decreased hemoglobin level

D

Increased triglyceride and cholesterol levels

Ans.

D

Explanation:

Vit B6 deficiency will not cause increased triglyceride and cholesterol levels in serum.

It is best attributed to the metabolic effects of steroidal contraceptives.

Pyridoxal phosphate is a coenzyme involved in the metabolism of protein, carbohydrates and fat. In protein metabolism, Vit B6 participates in the decarboxylation of amino acids and the conversion of tryptophan to niacin or serotonin.